1. Field of the Invention
The invention relates to optical lens arrays and methods for making such arrays.
2. Discussion of the Related Art
Some living organisms have natural arrays of optical lenses. Examples of natural arrays of optical lenses include the compound eyes of many insects and the skeletons of brittle stars. In these natural arrays, the individual optical lenses are capable of forming separate images. Lens arrays that simultaneously form multiple images have many potential applications. These applications have stimulated an interest in making such arrays artificially. For some applications, it is desirable to have arrays whose individual optical lenses have tunable optical parameters.
Examples of optical lenses with tunable focal lengths include variable compound lenses and electro-wetting controlled droplet lenses. A variable compound lens includes two spherical lenses and a mechanical device for varying the distance between the two spherical lenses. Varying the distance between the two spherical lenses varies the overall focal length of the compound lens. An electro-wetting controlled droplet lens includes a liquid droplet, a non-wettable substrate to support the droplet, and a voltage source to apply a voltage across the droplet. The voltage produces electro-wetting forces between the droplet and substrate. The electro-wetting forces redistribute the liquid of the droplet thereby changing the droplet's surface curvature and the focal length of the droplet lens.
Artificial arrays could provide for tunable focal lengths by incorporating tunable compound lenses or electro-wetting controlled droplet lenses. Nevertheless, compact arrays of such lenses are often inconvenient or complex because of the need for devices to enable tuning of each lens therein. Simple tunable artificial lens arrays are desirable.